1. Field of the Invention
The present invention relates to access control, and, more particularly, to manually operated, electronically keyed locks and locking processes suitable for retrofitting existing appliances.
2. Description of the Related Art
Current designs for maintaining security of containers such as bank safe deposit boxes require attended access and, all too frequently, dual keys, to allow access to the various containers maintained. We have found that the use of dual keys has become increasingly expensive in terms of man hours consumed by the employees of the bank providing attendance to the customers of the bank. Historically, safe deposit locks as well as other locks, have used a keyed cylinder that is offset from the centerline of the casing for the lock, within the body immediately behind the front plate of the safe deposit door. It was the object of this design to accommodate a full sized set of mechanical tumblers within the casing immediately behind the front plate of the door. The economics of safe deposit box rental require that the casing of the lock be made narrow in order to provide a high degree of security for the door while minimizing the loss of volume of the door due to the presence of the casing for the lock. The offsetting of the centerline of the keyway in turn allows the use of a more conventional and secure design within the very narrow compartment doors, as well as within taller doors. By the expedient of placing the cylinder of the lock in the lower portion of the casing, below the centerline of the casing and vault, the key could lift a set of larger tumblers without requiring an undesirably larger lock casing. The economy of providing uniform lock design, over the years, for differing applications has resulted in an existing installed base of millions of these locks. While not all of these locks rely upon offset keyed cylinders (referred to as “noses” in the trade), many do.
Four major lock manufacturers currently continue to produce locks with offset keyed cylinders, while at least two other manufacturer that have discontinued production, continue to have a large installed base. One of the most popular offset locks in the current market is the 4440 series left hand and right hand model manufactured by Sargent and Greenleaf. We have noticed a need to retrofit existing offset keyed cylinder locks with electro-mechanical locks, without expensive and inconvenient replacement of the doors, in order to minimize the man hours consumed by employees of banks that provide attendance to the customers, while the customers open their safe deposit doors, with a mechanical enhancement of blocking strength as well as an improvement of security over other processes, without a complex electrical contact system.
We have also noticed that authorized service mechanics often open locked mechanical safe deposit locks by first drilling a hole through the face of the cylinder plug, threading a sheet metal or self tapping screw into the hole and pulling the inserted screw with either a nose puller or claw hammer until the face of the cylinder breaks away to allow removal of the cylinder plug. The removal of the cylinder plug allows direct and immediate frontal manipulation of the tumblers until the lock is unlocked. Consequently, even though the faceplate of the safe deposit door may itself be strong enough to resist casual tampering, the susceptibility of the cylinder plug to quick removal by a single application of brute force deleteriously reduces the security of the entire drawer.
The Electronic Security System of U.S. Pat. No. 5,745,044 and U.S. Pat. No. 5,140,317 issued to Hyatt et al., is currently used to lock pay telephones. This design blocks a locking bolt, but does so from what we believe is a geometrically disadvantageous point. By virtue of the separate direct blocking of a bolt by a solenoid, the bolt is blocked off center from the centerline of the bolt. Moreover, the physically large lock cylinder and the inter-device discrete wiring between the solenoid and the other components inside the casing, as well as the electrical contact system for the lock cylinder, create several problems in our opinion. Furthermore, the difficulty of manufacture and installation of wiring, and the absence of both miniaturization and offsetting of the bolt blocking, suggest that there is little practical prospect of retrofitting the many existing offset nose locks. In addition, the routing and use of discrete wires causes problems of reliability and quality during manufacture and usage, absent tedious careful and consistent monitoring.
The rotatable keypad operated solenoid lock of Butterweck, et al, U.S. Pat. No. 5,845,523 for an Electronic Input And Dial Entry Lock, and the other various locks mentioned in that patent such as U.S. Pat. No. 4,831,851 for a Combination/electronic Lock System by Larson, U.S. Pat. No. 4,967,577 for an Electronic Lock With Manual Override by Gartner, et al, U.S. Pat. No. 4,899,562 for an Electronic Door Lock by Gartner, and U.S. Pat. No. 4,904,984 for a Combination Lock With An Additional Security Lock by Gartner, are variations of a dial operated combination lock, and lack the security, reliability and economy traditionally demanded for safe deposit boxes and drawers, while the Lock For A Safe-Deposit Box of Chieh-Chen Yen, et al., U.S. Pat. No. 5,495,733 inconveniently relies upon different keys for the renter of the safe deposit box and for the clerk of the bank, as well as a manually operated keypad.